Method of implanting a deformable intraocular corrective lens

ABSTRACT

A deformable, artificial intraocular contact lens for implantation into the human eye to correct normal-vision problems. The lens may be positioned posteriorly from the iris, resting against the anterior surface of the posterior capsule&#39;s natural lens. Alternatively, the lens may be positioned in the anterior chamber of the eye. The implanted lens works in conjunction with the cornea and natural lens to provide proper vision, as a substitute for regular contact lens, spectacles, and radial keratotomy. The lens may be designed from a rigid or semi-rigid material. Due to the thinness of the structure, the lens may be rolled and inserted into the eye, minimizing both the length of the corneal incision and the stretching of the cornea.

This is a divisional application of U.S. patent application Ser. No.08/914,767 filed Aug. 20, 1997, now U.S. Pat. No. 6,096,077 for“Deformable Intraocular Corrective Lens.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a deformable intraocular contact lensto correct vision problems, which lens is inserted into the eye anteriorto the natural lens and has a functional design which minimizes cuttingor stretching of the cornea to do so.

2. Description of the Related Art

Doctors trained in ophthalmology routinely surgically extractcataract-impaired lenses from patients' eyes and subsequently implantartificial lenses to prevent blindness. The artificial lens is typicallymanufactured from polymethylmethacrylate (PMMA), an acrylic plastic.PMMA is a preferred material because it is biologically compatible withthe tissue of the eye, and it does not degrade over time.

Over the last 50 years, the success rate for implanting theseintraocular lenses has improved to the point that surgeons now want toimplant intraocular contact lenses anterior to the natural lenses tocorrect common vision problems, such as myopia (near-sightedness),hypermetropia (far-sightedness), and astigmatism (aberration in theconvexity of the optic lens or cornea) However, using an intraocularlens for vision correction is currently problematic. in order to insertan intraocular lens, an incision of approximately 10 mm is made throughthe cornea or sclera. The new lens is passed through the incision intothe anterior chamber of the eye. The inserted lens is then positionedover the pupil and anchored either anteriorly to or posteriorly from theiris. Unfortunately, the making of the incision causes astigmatism ofthe cornea.

Experience from cataract surgeries shows that the astigmatism will bereduced if smaller incision is made. Is follows that if the lens couldbe manipulated through a smaller incision, it will reduce the severityof the astigmatism. The optical portion of the intraocular lens, though,must have a diameter of at least is approximately 6 mm in order toproperly cover the pupil. So, the only way to pass a lens through asmaller incision is to first fold the lens into a U-shape or roll it so,that the opposite edges are overlapping. However, currently designedPMMA lenses are rigid and too brittle to be rolled or folded. While itis known that a material which is rigid at a given thickness may beflexible at a lesser thickness, the maximum material thickness underwhich PMMA. is flexible is approximately 0.25 mm. This thickness is toothin for use in a conventional contact lens because of the lens' opticsrequirements.

A lens has a convex lenticular surface into which incident light passes.The lens also has a posterior surface, opposite the lenticular surface,from which the refracted light exits. The posterior surface may beconvex, planar or concave. The power of the lens is determined by thecurvature of the lenticular and posterior surfaces. Because the opticalportion of the contact lens is approximately 6 mm wide and the thickestportion is at the center of the lens, a conventional lens having amaximum thickness of under 0.25 mm at its center in order to be rolledcannot possess the requisite curvature to be optically useful.

Alternative lens materials are also currently used for the replacementsof the natural lenses of cataract patients. One such alternative lensmaterial is an acrylic that has a lower molecular weight than PMMA. Thislower-weight acrylic lens is softer than PMMA so it can be folded in aU-shape. However, if not handled very carefully, the lower-weightacrylic will crease, rendering it unusable. In addition, the material issoft enough to adhere to itself if it is rolled or folded far enough toallow overlapping.

Another alternative lens material is silicone, the same material that isused in breast implants. The silicone collects protein in some patients,giving a yellow appearance and reducing the passage of light. Theprotein can become so dense as to create the appearance of a secondarycataract, significantly reducing the patient's ability to see. This isusually a lesser concern for cataract patient, when compared to theblindness which would result from the cataract. Also, most cataractpatients tend to be elderly so the protein build-up might not advancetoo far during their lifetimes. For some cataract patients, though, theprotein build-up necessitates that the silicone lens be removed andreplaced. because of the problems associated with protein build-up,silicone cannot be used to make long-term intraocular contact lenses forimplantation into younger persons.

Two inventions for a deformable intraocular lens are set forth in U.S.Pat. No. 4,573,998 issued March 1986, to Mazzocco; and U.S. Pat. No.5,522,890 issued June 1996, to Nakajima et al. These inventions employ alens made of a molded elastic material. They do not suggest the use ofPMMA.

Other inventions generally related to the art of optical lenses include:U.S. Pat. No. 4,254,509 issued March 1981, to Tennant (AccommodatingIntraocular Implant); U.S. Pat. No. 4,585,456 issued April 1986, toBlackmore (Corrective Lens for the Natural Lens of the Eye); U.S. Pat.No. 4,655,775 issued April 1987, to Clasby (Intraocular Lens withRidges); U.S. Pat. No. 4,769,035 issued September 1988, to Kelman(Artificial Lens and the Method for Implanting Such Lens); U.S. Pat. No.4,795,462 issued January 1989, to Grendahl (Cylindrically Segmented Zoneof focus Artificial Lens); U.S. Pat. No. 4,816,032 issued March 1989, toHetland (Arrangement in an Intraocular Anterior Chamber Lens); U.S. Pat.No. 4,950,290 issued August 1990, to Kamerling (Posterior ChamberIntraocular Lens); U.S. Pat. No. 4,994,080 issued February 1991, toShepard (Optical Lens Having at Least One Stenopaeic Opening Located inthe Central Area Thereof); U.S. Pat. No. 5,076,684 issued December 1991,to Simpson et al. (Multi-Focal Diffractive Ophthalmic Lenses); U.S. Pat.No. 5,098,444 issued March 1992, to Feaster (Epiphakic Intraocular Lensand Process of Implantation); U.S. Pat. No. 5,166,711 issued November1992, to Portney (Multifocal Ophthalmic Lens); U.S. Pat. No. 5,229,797issued July 1993, to Futhey et al. (Multifocal Diffractive OphthalmicLenses); U.S. Pat. No. 5,258,025 issued November 1993 to Fedorov et al.(Corrective Intraocular Lens); U.S. Pat. No. 5,480,428 issued January1996, to Fedorov et al. (Corrective Intraocular Lens). None of theseinventions solves the above-disclosed problems associated with currentlyknown deformable intraocular lenses.

Thus, a need exists for a deformable intraocular contact lens whichrequires a minimal incision through the cornea, but does not, possessthe drawbacks associated with the currently known, alternative lensmaterials. None of the above inventions and patents, taken eithersingularly or in combination, is seen to describe such a lens as isachieved by the instant invention as claimed.

SUMMARY OF THE INVENTION

The present invention is a deformable intraocular contact lensconstructed from PMMA for rolled or folded insertion into the human eyeto correct common vision problems. The PMMA is deformable because allportions of the lens are manufactured to a thickness which is within apredetermined range of thicknesses. More particularly, at the first endof the range, the thickness of the lens is less than a maximum materialthickness, the threshold under which the PMMA is flexible. At the secondend of the range, the thickness of the lens is also greater than aminimum material thickness, the threshold above which the lens materialwill retain its pre-flexed shape subsequent to flexing. The novel designalso enables the deformable PMMA lens to possess any desired convexityor concavity which would be required for vision correction. Of course,the deformable lens of the present invention may also be constructedfrom any other biologically compatible material that can be manufacturedthinners than a pre-determined maximum material thickness to be rolledor folded for passage through a small incision in the cornea or sclera.The improved lens replaces the need for spectacles, contact lenses orradial keratotomy.

The intraocular contact lens has an anterior convex lenticular surface.The posterior surface of the lens comprises a planar, central disk whichis surrounded by a series of concentric, planar, annular rings ofincreasing diameter. The annular rings are parallel to each other and tothe central disk. The central disk and annular rings are alsoperpendicular to a radial axis passing though the apex of the lenticularsurface. In combination, the central disk and the series of annularrings form a series of steps extending radially from the disk across theposterior surface to maintain a close proximity to the lenticularsurface.

The thickness of the lens between the central disk of the posteriorsurface and the apex of the lenticular surface must be less than apredetermined maximum thickness. The predetermined maximum thickness isthe thickness under which the material may be rolled or folded withoutexceeding the elastic limit of the selected lens material. For a lensconstructed of PMMA, the maximum thickness between the posterior surfaceand the apex of the lenticular surface should be less than or equal to0.25 mm.

The thickness of the lens at the periphery of the central disk must begreater than a pre-determined minimum thickness. The predeterminedminimum thickness is the thickness above which the lens material willretain its pre-flexed shape subsequent to flexing. The minimum thicknessis determined by the manufacturing process and the strength of the lensmaterial. For PMMA, the minimum thickness between the lenticular surfaceand the periphery or the central disk should be greater than or equal to0.0125 mm.

The radial width of the central disk of the posterior surface also fallswithin a predetermined range. The thicker the lens is at its apex, thefarther the radial width may extend before the periphery of the centraldisk approaches the predetermined minimum thickness. The specific rangeof radial widths is determined by both the convexity of the lenticularsurface and the thickness of the lens at its apex.

Similar to the central disk, the thickness between the lenticularsurface and the posterior surface of the lens at the internal diameterof each annular ring should be less than or equal to the predeterminedmaximum thickness. The thickness between the lenticular surface and theposterior surface of the lens at the external diameter of each annularring should be greater than or equal to the predetermined minimumthickness. The radial width of the annular rings will be within apredetermined range of lengths which is determined by the convexity ofthe lenticular surface and the thickness of the lens at the internaldiameter of the annular ring. The greater the thickness of the lens atthe internal diameter of the annular ring, the greater the radial lengthmay be extended before the exterior diameter approaches thepredetermined minimum thickness.

If an imaginary line is drawn to connect the posterior surface'sinternal diameters of the annular rings and the center of the centraldisk, the imaginary line will form an arc or parabola, depending on thevarious thicknesses chosen. This imaginary line forms the effectiveposterior surface. By changing the thicknesses and widths of the centraldisk and annular rings, the effective is posterior surface may be shapedas desired. This is particularly relevant for applications in which theimplanted lens is implanted posterior from the iris, as furtherdescribed below. This is because the effective posterior surface maythereby be constructed in a predetermined shape which enables theimplanted lens to be properly rested against the anterior surface of thenatural lens capsule.

In one alternate embodiment of the invention, the central disk andannular rings of the posterior surface are not planar. Rather, eachsurface of the central disk and annular rings is convex. In a secondalternate embodiment of the invention, each surface of the central diskand annular rings is concave. Thereby, particular degrees of convexityor concavity of each section of the posterior surface may be chosen tofurther help obtain particular focusing powers for different lenses.Also, in any of these embodiments, the central portion and annular ringsof the lens may be of a symmetric or asymmetric ovular shape forcorrection of astigmatisms.

The periphery of the optical portion comprises a parallel lenticulararea. The parallel lenticular area is of uniform thickness. The parallellenticular area prevents the phenomenon known as edge effects whichoccurs if the optical portion of the lens does not adequately cover theperiphery of the pupil. The edge effects are produced in varioussituations including when overhead lights are illuminated in lowlighting situations, such as in roadway tunnels.

An anchoring means is attached to the optical portion to securelyposition the deformable intraocular contact lens anteriorly to thenatural lens of the eye. The contact lens also has a non-opticaltransition area interconnecting the anchoring means to the opticalportion of the lens. The transition area has a thickness ofapproximately 0.025 mm. The anchoring means comprises a pair of hapticfingers extending from the transition area and circumvolving the opticallens. The thickness of the haptic fingers is preselected to provide theoptimal combination of strength and flexibility. Preferably, thethickness of each of the haptic finger is approximately 0.076 mm. Theouter circumference of the haptic finger comprises the haptic edge. Thehaptic edge of the implanted lens is biased against the intraoculartissues. The thickness of the haptic edge is preselected to provideminimal stress to the eye tissues. Preferably, the thickness if thehaptic edge is approximately 0.125 mm.

Once rolled and passed through the cornea, the implanted contact lensmay be placed in either of two selected positions. Specifically, theimplanted lens may be positioned anterior to she iris, in the anteriorchamber of the of eye. If this position is chosen, the haptic edge ofeach of the haptic fingers will be biased against the trabeculum. Oncepositioned and allowed to unroll, the implanted lens will return to itsoriginal shape.

Alternatively, the implanted lens may be positioned posteriorly from theiris, and rest against the capsule of the natural lens of the eye. Ifthis position is chosen, the haptic edge of each of the haptic fingerswill be biased against the zonulas or ciliary sulcus. The implanted lensis able to be placed posteriorly from the iris because of the thinnessof the implanted lens. The lens' thinness provides adequate clearancebetween the natural lens when at rest and the posteriorly positioned,implanted lens. The biconvex natural lens is in its most curved positionwhen at rest. Contraction of the zonulas places tension on the capsule,flattening the curvature of the natural lens. Thus, with the implantedlens in position, the natural lens will continue to have the ability tochange shape, without the possibility of injury arising from contactwith the implanted lens.

Accordingly, it is a principal object of the invention to provide adeformable intraocular contact lens which requires a minimal incisionthrough, or stretching of, the cornea for insertion.

It is another object of the invention to provide a deformableintraocular lens from a material such as PMMA which is biologicallycompatible with the eye tissue but will neither crease nor adhere toitself when rolled, nor cause eye disease as it ages.

It is a further object of the invention to provide an intraocularcontact lens which may be positioned either anterior or posterior to theiris.

Still another object of the invention is to provide an intraocular lensfor correcting common vision problems, such as myopia, hypermetropia,and astigmatism.

It is an object of the invention to provide improved elements andarrangements thereof in a deformable intraocular contact lens for thepurposes described which is inexpensive, dependable and fully effectivein accomplishing its intended purposes.

These and other objects of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a deformable intraocular contact lens accordingto the present invention.

FIG. 2 is a cross-sectional view of the intraocular contact lens drawnalong line 2—2.

FIG. 3 is an enlarged, fragmented view of the optical portion andtransition area of the lens depicted in FIG. 2.

FIG. 4 is a fragmented view of the anchoring means and the transitionarea of the lens depicted in FIG. 2.

FIG. 5 is a cross-sectional fragmented view of a second embodiment ofthe invention.

FIG. 6 is a cross-sectional fragmented view of a third embodiment of theinvention.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a deformable intraocular lens is constructedfrom a material which is biologically compatible with the eye tissuesfor correction of normal-vision problems.

FIG. 1 is a top view of the deformable intraocular contact lens 8according to the present invention. The deformable intraocular lens 8 isconstructed of a material which is biologically compatible with thenatural lens of the eye. The optical portion 9 of the lens 8 has ananterior convex lenticular surface 10. The periphery of the opticalportion 9 comprises a parallel lenticular area 11. The parallellenticular area 11 is of uniform thickness and is for preventing thephenomenon known as edge effects. A

FIG. 1 is a top view of the deformable intraocular contact lens 8according to the present invention. The deformable intraocular lens 8 isconstructed of a material which is biologically compatible with thenatural lens of the eye. The optical portion 9 of the lens 8 has ananterior convex lenticular surface 10. The periphery of the opticalportion 9 comprises a parallel lenticular area 11. The parallellenticular area 11 is of uniform thickness and is for preventing thephenomenon known as edge effects. A

FIG. 2 is a cross-sectional view of the intraocular contact lens 8 drawnalong line 2—2. FIG. 3 is a fragmented view or the: optical portion 9and transition area 15 of the lens 8 depicted in FIG. 2. FIG. 4 is afragmented view of the anchoring means and the transition area 15 of thelens depicted in FIG. 2. These three figures depict, to varying degrees,the anterior lenticular convex surface 10 of the optic portion 9. Theposterior surface 20 is also depicted therein. The posterior surface 20comprises a central disk 21 which is surrounded by a plurality ofannular rings 22. The central disk 21 and series of annular rings 22form a series of radial steps across the posterior surface 20 tomaintain a close proximity to the lenticular surface 10. The thicknessof the central disk 21 at the apex of the lenticular surface 10 is lessthan or equal to a predetermined maximum thickness so that thedeformable intraocular contact lens 8 may be rolled without exceedingthe elastic limit of the lens material. The thickness of the peripheryof the central disk 21 is greater than or equal to a predeterminedminimum thickness so that the deformable intraocular contact lens 8 willretain. its pre-flexed shape subsequent to being rolled.

The surfaces of each annular ring 22 are planar and parallel with thecentral disk 21. Each annular ring 22 has an internal diameter 22 a andan external diameter 22 b. The thickness of the contact lens 8 betweenthe internal diameter 22 a of the posterior surface's 20 annular rings22 and the lenticular surface 10 is less than or equal to thepredetermined maximum thickness. The thickness of the contact lens 8between the external diameter 22 b of the posterior surface's 20 annularrings 22 and the lenticular surface 10 is greater than or equal to thepredetermined minimum thickness.

The outer most ring 22 is adjacent to the posterior surface 25 of theparallel lenticular area 11.

FIG. 3 further includes a dashed line 28 depicting an imaginary linewhich connects the center of the central disk 21 and the edges internaldiameters 21 a of the annular rings 22 of the posterior surface 20. Theimaginary line depicted by dashed line 28 is the effective posteriorsurface of the optical portion 9 of the deformable intraocular contactlens 8.

FIG. 2 through FIG. 4 further depict the parallel lenticular area 11surrounding the periphery of the optical portion 9. The parallellenticular area 11 is of uniform thickness and is for preventing edgeeffects. The transition area 15 surrounds the parallel lenticular area11. The anchoring means extend from the transition area 15. FIG. 2 andFIG. 4 further depicts the anchoring means. The anchoring meanscomprises a pair of haptic fingers 17 circumvolving the optical portion9 of the deformable intraocular contact lens 8.

FIG. 5 is a cross-sectional fragmented view of a second embodiment ofthe invention. In this alternate embodiment, the anterior lenticularsurface 510 of the optic portion 509 is of the same convex shape as inthe previously described embodiment. The posterior surface 520 comprisesa central disk 521 which is surrounded by a plurality of annular rings522. The central disk 521 and series of annular rings 522 form a seriesof radial steps across the posterior surface 520 to maintain a closeproximity to the lenticular surface 510.

In this embodiment, the surfaces of the central disk 521 and each of theannular rings 522 are convex. The thickness of the central disk 521 atthe apex of the lenticular surface 10 is less than or equal to thepredetermined maximum thickness. The thickness of the periphery of thecentral disk 521 is greater than or equal to a predetermined minimumthickness.

Each annular ring 521 has an internal diameter 522 a and an externaldiameter 522 b. The thickness of the contact lens between the internaldiameter 522 a of the posterior surface's 520 annular rings 522 and thelenticular surface 510 is less than or equal to the predeterminedmaximum thickness. The thickness of the contact lens between theexternal diameter 522 b of the posterior surface's 520 annular rings 522and the lenticular surface 510 is greater than or equal to thepredetermined minimum thickness. The parallel lenticular area 511surrounds the periphery of the optical portion 509. The parallellenticular area 511 is of uniform thickness. The transition area 515surrounds the parallel lenticular area 511. The anchoring means (notshown) extends from the transition area 515. The outer most annular ringis adjacent to the posterior surface 525 of the parallel lenticular area511.

The outer most ring 22 is adjacent to the posterior surface 525 of theparallel lenticular area 511.

FIG. 6 is a cross-sectional fragmented view of a third embodiment of theinvention. In this alternate embodiment, the anterior lenticular surface610 of the optic portion 609 is of the same convex shape as in thepreviously described embodiments. The posterior surface 620 comprises acentral disk 621 which is surrounded by a plurality of annular rings622. The central disk 621 and series of annular rings 622 form a seriesof radial steps across the posterior surface 620 to maintain a closeproximity to the lenticular surface 610.

In this embodiment, the surfaces of the central disk 621 and each of theannular rings 622 are concave. The thickness of the central disk 621 atthe periphery of the central disk 621 is less than or equal to thepredetermined maximum thickness. The thickness of the lens between theapex of the lenticular surface 610 and the central disk 621 is greaterthan or equal to a predetermined minimum thickness.

Each annular ring 621 has an internal diameter 622 a and an externaldiameter 622 b. The thickness of the contact lens between the internaldiameter 622 a of the posterior surface's 620 annular rings 622 and thelenticular surface 610 is greater than or equal to the predeterminedminimum thickness. The thickness of the contact lens between theexternal diameter 622 b of the posterior surface's 620 annular rings 622and the lenticular surface 610 is less than or equal to thepredetermined maximum thickness. The parallel lenticular area 611surrounds the periphery of the optical portion 609. the parallellenticular area 611 is of uniform thickness. The transition area 615surrounds the parallel lenticular area 611. The anchoring means (notshown) extends from the transition area 615. The outermost annular ringis adjacent to the posterior surface 625 of the parallel lenticular area611.

The outer most ring 22 is adjacent to the posterior surface 625 of theparallel lenticular area 611.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

We claim:
 1. A method of correcting impaired vision comprising the stepsof: a. making an incision for access to the anterior chamber of an eyehaving a length less than 4 mm; b. providing a corrective lens formed ofpolymethylmethacrylate material having a thickness no greater than 0.25mm, having a diameter of 6 mm. c. integrally providing support hapticsfor anchoring the corrective lens; d. rolling the corrective lens andthe support haptics without exceeding the elastic limit of thepolymethylmethacrylate material into a rolled package; e. inserting therolled package into the anterior chamber of the eye via the incision; f.unrolling the rolled package internally of the anterior chamber; g.anchoring the haptics anteriorly of the natural lens of the eye in theanterior chamber; h. repairing the incision made in the eye.
 2. A methodof correcting impaired vision comprising the steps of. a. making anincision for access to the anterior chamber of an eye having a lengthless than 4 mm; b. providing a corrective lens formed ofpolymethylmethacrylate material having a thickness no greater than 0.25mm, having a diameter of 6 mm, the corrective lens having an anteriorconvex lenticular surface and a posterior surface, wherein saidposterior surface comprises a central disk which is radially surroundedby a series of annular rings found on said central disk in said seriesof annular rings forming a series of radial steps along said posteriorsurface. c. integrally providing an anchor for the corrective lenssupport haptics for anchoring the corrective lens; d. rolling thecorrective lens and the support haptics without exceeding the elasticlimit of the polymethylmethacrylate material into a rolled package; e.inserting the rolled package into the anterior chamber of the eye viathe incision; f. unrolling the rolled package internally of the anteriorchamber; g. anchoring the haptics anteriorly of the natural lens of theeye in the anterior chamber; h. repairing the incision made in the eye.